6.2 Incorporeal Entities
In general, concepts are either abstract or concrete, and this what makes the distinction between metaphysics and epistemology. Abstract objects include concepts such as numbers, mathematical functions, and philosophical relations and properties, such as redness, which has no space-time location.
In ontology and philosophy of mind, a non-physical entity is a spirit or being that exists outside physical reality. The dualist school supposes the existence of non-physical entities, such as the mind, but they usually consider it impossible for a non-physical mind to conceive the relationship that it has with the physical. It is impossible to explain philosophically the distinction between the physical and non-physical how they may affect each other.
Although their existence and nature are widely debated, since it seems impossible to demonstrate in any rigorous scientific manners, purported non-mental non-physical entities include things such as angels, demons, and ghosts. Therefore, describing these non-physical entities in philosophical terms is problematic, because if their existence is ever scientifically demonstrated, that would actually place them in the category of physical entities.
Incorporeal or uncarnate means without a physical body, presence or form. Many religions, including Judaism, Christianity, and Islam, reference is often made to God, spirits, and souls, while in ancient philosophy, any attenuated things such as air, aether, fire or light were considered incorporeal. This distinction is even more difficult in modern physics after the puzzling wave-particle duality that we reviewed in chapter III.